updated copyright info

LICENSE

api/v1/api.go

api/v1/api_files.go

api/v1/api_groups.go

api/v1/api_imports.go

api/v1/api_playlists.go

api/v1/types.go

api/v1/utils.go

cmd/tank/Makefile

cmd/tank/main.go

cmd/tank/web.go

importer/Makefile

importer/config.go

importer/importer.go

importer/session.go

importer/session_store.go

store/Makefile

store/config.go

store/files.go

store/groups.go